A steam leak in the heating network of the Lille metropolitan area has caused major disruptions to internet and phone services for hundreds of businesses and public services. The issue came to light after repeated serious steam leaks since late 2022, which led to hot steam seeping into underground areas. This steam melted the plastic casings of Orange’s telecommunications network and damaged the concrete covering of copper and fiber optic lines. As a result, temperatures in certain areas reached over 50 degrees Celsius, causing sudden outages in internet and landline telephone services for many subscribers. The legal case was brought before the Nanterre Economic Activities Court to determine who is responsible for the damage. The case involved Orange, the construction company Eiffage, and its subcontractors. Key issues included the poor performance of insulation materials used and errors in the assessment of the network’s flexibility. The court found that the long chain of industrial subcontractors was responsible for the network outages. When material failures occur in a complex system, claiming compensation and determining responsibility can be a long and expensive process. This case underscores the importance of legal expertise to gather evidence of operational damage and ensure that insurance companies provide coverage. It also raises concerns about whether fiber networks share the same underground pathways as high-risk pipelines, such as those carrying heating steam or gas. The situation has highlighted the need for better coordination and risk assessment in infrastructure planning. As cities continue to expand their networks for both heating and telecommunications, ensuring that these systems do not interfere with one another becomes increasingly important. This case serves as a reminder of the potential consequences of inadequate planning and the challenges of resolving disputes in complex industrial projects.